Background Few epidemiological investigations have focused on the influence of environmental temperature on human sperm quality. Here, we evaluated the potential association between ambient temperature and human sperm quality in Wuhan, China, and examined the interactive effect of particulate matter (PM2.5) and temperature. Methods 1780 males who had been living in Wuhan for no less than three months and received semen analysis at the Department of Reproductive Medicine in Renmin Hospital of Wuhan University between April 8, 2013 and June 30, 2015 were recruited. Daily mean meteorological data and air pollution data (PM2.5, O3 and NO2) in Wuhan between 2013 and 2015 were collected. A generalized linear model was used to explore the associations between ambient temperature and sperm quality (including sperm concentration, percentage of normal sperm morphology, and progressive motility) at 0–9, 10–14, 15–69, 70–90, and 0–90 days before semen examination, and the interaction between temperature and PM2.5. Results The associations between ambient temperature and sperm quality were an inverted U-shape at five exposure windows, except for a lag of 0–9 days for sperm concentration. A 1 °C increase in ambient temperature above the thresholds was associated with a 2.038 (1.292 ~ 2.783), 1.814 (1.217 ~ 2.411), 1.458 (1.138 ~ 1.777), 0.934(0.617 ~ 1.251) and 1.604 (1.258 ~ 1.951) decrease in the percentage of normal sperm morphology at lag 0–9, lag 10–14, lag 15–69, lag 70–90, and lag 0–90 days, respectively. The interaction p-values of PM2.5 and temperature were mostly less than 0.05 at five exposure windows. When ambient temperature exposure levels were above the thresholds, a 0.979 (0.659–1.299) and 3.559 (0.251 ~ 6.867) decrease in percentage of normal sperm morphology per 1 °C increase in temperature at lag 0–90 days was observed in the PM2.5 ≤ P50 group and PM2.5 > P50 group, respectively. Conclusions Our results indicate that exposure to ambient temperature has a threshold effect on sperm quality, and PM2.5 enhances the effect of temperature on sperm quality when temperatures are above the threshold.

BackgroundLimited studies have explored the association between gaseous pollutant exposures and male reproductive outcomes, and findings remained inconsistent.ObjectivesTo evaluate the potential association  between gaseous pollutants and semen quality within different exposure windows.Materials and MethodsWe adopted semen quality data of 1852 subjects who attended the Reproductive Medicine Center of Renmin Hospital at Wuhan University during January 1st, 2013, to August 3rd, 2015. A generalized linear model was employed to assess the relationship between each exposure variable and sperm parameters in different exposure windows.ResultsSO2 exposure with lag 0–90 days was significantly associated with decreased sperm concentration (β: −1.362; 95% CI: −1.844, −0.879), sperm count (β: −2.979; 95% CI: −4.267, −1.691), and PR (β: −0.551; 95% CI: −0.710, −0.393). Similar trends were observed for SO2 exposure with three other key periods (lag 0–9, 10–14, and 70–90 days). NO2 exposure with lag 0–90 days was also associated with decreased sperm concentration (β: −0.517; 95% CI: −1.006, −0.027), sperm count (β: −1.914; 95% CI: −3.214, −0.615), and PR (β: −0.264; 95% CI: −0.425, −0.102). No relationship between gaseous pollutant exposure and ejaculate volume was observed in any exposure window.Discussion and ConclusionOur study indicated a strong adverse effect of gaseous pollutants on semen quality outcomes during the sperm development. Gaseous pollution exposure appeared to be more detrimental in the initial phase of spermatogenesis.

Background Few epidemiological investigations have focused on the influence of environmental temperature on human sperm quality. Here, we evaluated the potential association between ambient temperature and human sperm quality in Wuhan, China, and examined the interactive effect of particulate matter (PM 2.5 ) and temperature. Methods 1780 males who had been living in Wuhan for no less than three months and received semen analysis at the Department of Reproductive Medicine in Renmin Hospital of Wuhan University between April 8, 2013 and June 30, 2015 were recruited. Daily mean meteorological data and air pollution data (PM 2.5 , O 3 and NO 2 ) in Wuhan between 2013 and 2015 were collected. A generalized linear model was used to explore the associations between ambient temperature and sperm quality (including sperm concentration, percentage of normal sperm morphology, and progressive motility) at 0–9, 10–14, 15–69, 70–90, and 0–90 days before semen examination, and the interaction between temperature and PM 2.5 . Results The associations between ambient temperature and sperm quality were an inverted U-shape at five exposure windows, except for a lag of 0–9 days for sperm concentration. A 1 °C increase in ambient temperature above the thresholds was associated with a 2.038 (1.292~2.783), 1.814 (1.217~2.411), 1.458 (1.138~1.777), 0.934(0.617~1.251) and 1.604 (1.258~1.951) decrease in the percentage of normal sperm morphology at lag 0–9, lag 10–14, lag 15–69, lag 70–90, and lag 0–90 days, respectively. The interaction p- values of PM 2.5 and temperature were mostly less than 0.05 at five exposure windows. When ambient temperature exposure levels were above the thresholds, a 0.979 (0.659-1.299) and 3.559 (0.251~6.867) decrease in percentage of normal sperm morphology per 1 °C increase in temperature at lag 0-90 days was observed in the PM 2.5 ≤ P 50 group and PM 2.5 > P 50 group, respectively. Conclusions Our results indicate that exposure to ambient temperature has a threshold effect on sperm quality, and PM 2.5 enhances the effect of temperature on sperm quality when temperatures are above the threshold.

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